Intelligence is the highest attribute of human beings. Different psychologists have defined intelligence differently. Lewis Terman explains intelligence as, “an ability to think on an abstract level.

David Wechsler defines intelligence as, “the aggregate or global capacity of an individual to act purposefully, to think rationally and to deal effectively with his environment.” On the basis of material used in the tests, intelligence tests can be classified as Verbal tests and Non-verbal tests of intelligence.

Intelligence tests that use pictures, designs, material objects, etc., to measure intelligence are called non-verbal tests of intelligence. In these tests language is not used to measure intelligence. In these tests subjects are not required to respond verbally to test items. Non-verbal tests are of two types viz.

1. Performance tests for e.g., Koh’s Block Design test, Dr. Bhatia’s Non Verbal test, Alexander’s Pass-along test, etc. and 

2. Paper-pencil tests for e.g., Raven’s Standard Progressive Matrices.